FIG. 1 is a prior art. It is well known that color can have a profound effect on how we feel both mentally and physically. The ancient Egyptians as well as the Native American Indians used color and colored light to heal. Blue color represents peace; Green color represents nature; Purple color represents royalty; and Yellow color represents happiness . . . etc., that is to say, different color temperature creates different atmosphere. In other words, people may like to have white light with a bit of yellow at one time, but may like to have white with a bit of blue at another time. A prior art of a color temperature adjustable lamp is shown in FIG. 1, a red (R) light emitted diode (LED), a green (G) light emitted diode, and a blue (B) light emitted diode are mounted on a substrate 10 to be adjusted for producing a desired color temperature to emit. Glue 15 encloses the three LEDs R, G, and B as a protection. The red LED electrically couples to a common electrode 124 and a first electrode lead 121. The green LED electrically couples to the common electrode 124 and a second electrode lead 122. The blue LED electrically couples to the common electrode 124 and a third electrode lead 123. The traditional color temperature adjustable lamp needs to control currents of three diodes R, G; and B to obtain desired color temperature atmosphere. To adjust three current variable components is a little complicated to an end user. It is desired to develop a color temperature adjustable lamp with lesser adjustable variable components.